Evolution of wheat spikes since the Neolithic revolution
Date:
February 2, 2023
Source:
University of Barcelona
Summary:
Around 12,000 years ago, the Neolithic revolution radically changed
the economy, diet and structure of the first human societies
in the Fertile Crescent of the Near East. With the beginning of
the cultivation of cereals -- such as wheat and barley -- and the
domestication of animals, the first cities emerged in a new social
context marked by a productive economy. Now, a study analyses
the evolution of wheat spikes since its cultivation began by the
inhabitants of ancient Mesopotamia -- the cradle of agriculture --
between the Tigris and the Euphrates.
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FULL STORY ========================================================================== Around 12,000 years ago, the Neolithic revolution radically changed the economy, diet and structure of the first human societies in the Fertile Crescent of the Near East. With the beginning of the cultivation of
cereals - - such as wheat and barley -- and the domestication of animals,
the first cities emerged in a new social context marked by a productive economy. Now, a study published in the journal Trends in Plant Science
and co-led by the University of Barcelona, the Agrotecnio centre and the University of Lleida, analyses the evolution of wheat spikes since its cultivation began by the inhabitants of ancient Mesopotamia -- the cradle
of agriculture in the world - - between the Tigris and the Euphrates.
==========================================================================
The authors of the study are Rut Sa'nchez-Bragado and Josep Llui's Araus- Ortega, from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo
A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry
Science and Engineering, and Gemma Molero, from the International Maize
and Wheat Improvement Center in Mexico, currently a researcher at KWS
Seeds Inc.
A cereal that changed human history The cultivation of wheat -- a grass
that became basic food -- represented a turning point in the progress
of human civilisation. Today it is the world's most important crop in
terms of food security, but EU data warn that the impact of climate
change could significantly increase its price and modify its production
process in certain areas of the world.
Throughout the domestication process of wheat, the plant phenotype has undergone both rapid (within a few hundred years) and slow (thousands
of years) changes, such as the weakening of the rachis, the increase in
seed size, and the reduction or disappearance of the awns. In particular,
awned and awnless wheat varieties are found all over the world, although
the latter tend to be abundant in regions with arid climates, especially
during the final stages of cultivation in late spring, a condition
typical of Mediterranean environments.
"It is important to conduct studies that show which wheat varieties are
best adapted to different environmental growing conditions, especially in
a context of climate change. Studying the past retrospectively can give
us an idea of the evolution of wheat cultivation over the millennia since agriculture appeared in ancient Mesopotamia," says Rut Sa'nchez-Bragado,
first author of the study, who got a PhD at the UB.
"Awns are organs of the spike that have traditionally been associated
with the plant's adaptations to drought conditions," says Josep Llui's
Araus, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology.
"However, archaeological and historical records show that the wheat spike
has existed predominantly with awns for more than ten millennia after
the domestication of wheat. It is not until the last millennium that
evidence shows in many cases the absence of awns, indicating a selection
by farmers - - probably in an undirected way -- against this organ,"
stresses Araus, one of the most cited authors in the world according to Clarivate Analytics' Highly Cited Researchers (2022).
"The role of wheat awns in their performance remains controversial despite decades of studies," says researcher Gustavo A. Slafer, corresponding
author of the study.
Spike awns: beneficial for the plant? Is the presence of awns on the
spike beneficial for the plant and the crops? Although there is no
scientific consensus, "everything suggests that in conditions where
the plant does not suffer from water stress, the extra photosynthetic
capacity of the awns does not compensate for other potential negative
effects (reduced susceptibility to fungal diseases, limitation in the
total number of large ones that an ear supports, etc.)," says Araus.
"However, in wetter climates the awns accumulate moisture and can promote
the spread of diseases," says Rut Sa'nchez-Bragado. "So, as the world's population is continuously growing, it is necessary to investigate the
role of the awned spikes in the changing conditions of our climate in
order to meet the world's demand for a primary food commodity such
as wheat." In arid conditions, the spikes -- including the awns --
"have better physiological characteristics than the leaves. In addition,
the awns allow the light captured by the crop to be more diffused,
which facilitates a better distribution of light energy and allows the
crop to photosynthesise more.
Therefore, in arid conditions, the awns can still be beneficial for the
crop, or at most, neutral," concludes Professor Josep Llui's Araus.
* RELATED_TOPICS
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# Food_and_Agriculture # Endangered_Plants # Nature
o Earth_&_Climate
# Earth_Science # Ecology # Global_Warming
o Fossils_&_Ruins
# Human_Evolution # Fossils # Charles_Darwin
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========================================================================== Story Source: Materials provided by University_of_Barcelona. Note:
Content may be edited for style and length.
========================================================================== Journal Reference:
1. Rut Sanchez-Bragado, Gemma Molero, Jose' L. Araus, Gustavo
A. Slafer.
Awned versus awnless wheat spikes: does it matter? Trends in Plant
Science, 2022; DOI: 10.1016/j.tplants.2022.10.010 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2023/02/230202153525.htm
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